1st issue : My system had a beautiful screensaver, it was a 3d cube slideshow picking one image randomly in a folder, the cube was rotating, zooming and there were some lighting and fireworks. It has now been replaced by the "simple locker" in the Screen Locker settings of Kde. I've been trying to put it back as it was for 3 hours now but couldn't find it. I'm not sure if it was part of kde or from another source but I would be grateful to anyone who knows about this screensaver.

2nd issue : Trying to change the login screen of Kde, fails consistently. Whether in themed greeter mode or choosing a background image, the result is not the chosen background. After applying the changes it messes up the application appearance settings as a bonus (Edit : applying the changes is not even necessary to mess it up. barely going in the Login Screen settings without doing anything and then closing System Settings is enough!!!).

1st issue: Which graphic card and with non-free driver or not? E.g. Nvidia doesn't work with 3.10 at the moment (lets hope the debian maintainers will do something; Nvidia hasn't release a working patch/new version fixing it so far [as usual]). You have to stick with 3.9 for the moment if you use those.

2nd issue: No real idea (I am not a KDE user), but have you tried creating a new dummy user and changing settings there? Maybe the new version chocks on some old settings.

_________________MfG. DonKult
"I never make stupid mistakes. Only very, very clever ones." ~ The Doctor